The invention relates to fleet management for vehicles that operate on batteries or fuel cells and, in particular, to a method of determining available vehicle range relative to GPS (global position satellite) position readings and vehicle charge level parameters for each such fleet vehicle, as determined in real time.
The refueling and maintenance infrastructure for fleets of non-petroleum fueled vehicles, mainly electric and fuel cell vehicles, has not yet developed. Without such infrastructure, the utility of a fleet of such vehicles is limited because refueling and power pack maintenance may not be readily available to vehicles whose range is exhausted or low. What is needed is a real-time vehicle management and dispatch system, having a way to calculate and communicate range parameters of the vehicles to a base station computer system in order to dispatch vehicles to tasks without the risk of becoming stranded while accomplishing assigned tasks. The system also schedules refueling and maintenance of fleet vehicles.
In U.S. Pat. No. 5,904,727 to S. Prabhakaran teaches mapping of fleet vehicle locations at a remote base station using a graphical display. The display also indicates identification, motion status, including speed, nearest intersection and destination. Jobs are assigned to vehicles based upon an evaluation by a fleet manager at a base station.
In U.S. Pat. No. 5,922,040 to S. Prabhakaran teaches a fleet management system having a main processor and client processors capable of viewing a display through the main processor. The main processor can be associated with mobile information centers, which provide graphical data to fleet vehicles.
A published PCT application, WO 02/17184 in the name of W. Bromley et al., describes a real-time, remote, wireless vehicle monitoring system, formerly made and sold by Nexiq of Sterling Heights, Michigan. The system uses the Internet, accessed by fleet vehicles to communication information enabling the remote monitoring, diagnosis and reprogramming of commercial vehicles, regardless of location. See www.nexiq.com. The system claims to continuously monitor up to 600 data points on a vehicle.
Parview Systems makes golf carts having a processor board, made by Applied Telematics of Columbia, Md. with a GPS chip and a video display. The display shows the position of the golf cart, as well as a map of a hole being played and the distance to the hole. The system is similar to one described in international patent document WO 93/12439 in the name of T. Gunthorpe et al. The Parview golf cart may be seen on the website ww.applied-telematics.net. The circuit board features an Intel 206 MHz StrongARM SA1110 processor, according to the website, along with power management for the board and flat panel display drivers. With power management, the board takes less than 2 watts at full operation, and has an automatic idling feature that suspends power to the display when the cart is not in active use. The system has three serial ports that are allocated to GPS, radio connections, and one is a spare for future expansion. Other functions implemented on the single-board computer include PCMCIA, a Codec, digital I/O, and analog inputs.
A fleet of electric or fuel cell vehicles contains a number of vehicles, each with a power pack that must be periodically recharged. For example, a small electric vehicle like a Neighborhood Electric Vehicle (NEV) carries six batteries that provide a range of between 20 to 30 miles depending mainly on the state of charge and secondarily on the cell condition of the batteries. Such electric cars are presently being used as taxis in cities such as Sacramento, Calif. where ElectriCab Taxi Company, assignee of the present invention, has a fleet of such vehicles. One of the problems faced by such a fleet is the possibility of lack of range while carrying fares.
So, while auto-location is known for electric vehicles and mapping and position location is known in the field of fleet management, there is yet a need for aiding available electric and fuel cell refueling and cell maintenance infrastructure which is thin in comparison to the infrastructure available for petroleum fueled vehicles.
The present invention is a method for determining range relative to a dynamic GPS position of each vehicle in a fleet of electric and fuel cell vehicles and using this information for optimizing vehicle dispatch in real time. Each vehicle periodically reports power pack parameters, particularly remaining voltage sag and remaining voltage. GPS position and other parameters are also reported to a base station where a central computer records the information into a database and displays information to a dispatcher using a graphical user interface (GUI). The dispatcher can then interpret the information and either assign future tasks or direct vehicles for refueling or maintenance. Each vehicle has parameter collecting and reporting instrumentation, such as an odometer reader and a power pack stored energy reader that include other key power cell parameters such as cell temperature, voltage sag, individual cell voltage, as well as a GPS sensor and reader, all reporting data to a base station via a wireless network. The network may use an existing voice channel radio link, a separate dedicated radio link for the network, or a virtual private network using the Internet. Existing smart batteries and fuel cells already report remaining charge to dashboard instruments in vehicles being sold today. This information may be used as the power pack charge reader. Vehicular GPS sensors with display capability have been sold for several years. At the base station, position data and power cell data, such as remaining stored charge, are continuously monitored and fed to a database which also contains range calibration data for each vehicle. This allows the computer to predict remaining range based upon remaining stored energy by comparison to the calibration data for each vehicle. The database may also contain static information, such as the time that the vehicle driver started work and his or her scheduled quitting time. Basic vehicle information, such as identification, as well as present position and remaining range can be displayed to a dispatcher on a map for new job assignments. The dispatcher can click on a particular vehicle on the map to see details in the database regarding reported parameters.
In a second embodiment, the vehicle carries the calibration data so that range can be predicted aboard each vehicle using the power pack parameters. In this situation each vehicle reports remaining range, as determined by on-board data, and GPS position and basic vehicle information. This information is used for dispatch of vehicles from the base station and as system information for the vehicle driver.